泥炭藓煤热模拟系列二阶导数红外光谱研究

泥炭藓煤热模拟系列二阶导数红外光谱研究彭文世，陈德玉（中国科学院广州地球化学研究所．广州５１０６４０）关键词泥炭藓煤，热模拟，二阶导数红外光谱许多科学家曾用红外光谱技术研究过煤和干酪根的热演化问题：详细讨论了不同变质程度的煤和沥青的红外光谱［１］；利...     

强天气过程中近地面层风速的非线性动力学特征

强天气过程中大气边界层不同尺度运动之间存在强烈的相互作用,这种相互作用使得近地层风速的变化表现出很强的非线性,风速的非线性特征可以用近代非线性物理中奇异性、大偏差和多重分形等特征量来刻划.作者研究了两次沙尘暴和一次冷锋时期超声风温仪观测资料的这些特征.4组资料奇异指数的概率分布基本一致,只有最强的奇异性存在差异.但最大风速的奇异性并不是最强的.风速的大偏差特征表明,不同时间长度相同的风速时间序列中出现某种极值的概率几乎不变,而大偏差谱能反映不同天气系统影响的差异,天气系统越强,越能维持涡旋运动规律不变.     

海岸带浅海水深高光谱遥感反演方法研究

近红外波段(760~900 nm)反射率对水深最为敏感,通过波段比值方法可以提高与水深的相关性,而711nm处反射率一阶微分值与水深的相关系数高达-0.87。对于近岸混浊度高的样本,单波段和比值模型反演效果不好,平均相对误差均高于30%;而光谱微分模型的精度较好,平均相对误差为17%。研究结果证明:水体反射率的一阶微分可以有效地削弱水质变化给水深反演带来的误差。     

多重分形方法在涡旋遥感信息处理提取中的应用研究

目前提取遥感影像中的涡旋信息主要用边缘探测技术,例如Canny算子和Hough算子等,然而由于涡旋信息和遥感影像本身的复杂性和模糊性,用传统的方法不能取得理想的提取结果.基于多重分形技术,利用海洋涡旋信息的物理特征时空形态的自相似性来提取涡旋,用NASA MODIS,Sea WiFS和NOAA在典型海区如边界流的卫星影像进行试验,研究结果表明,用多重分形方法获取的涡旋信息非常有利于对海洋涡旋的深刻认识和分析研究.     

青海门源6.4级地震兰新高铁沿线强震数据分析

基于2016-01-21青海门源6.4级地震,通过分析高铁沿线台站强震数据的峰值加速度、峰值速度和仪器烈度值表明,将实时仪器烈度值作为高铁地震监控系统的报警参数受场地条件影响较小。利用沿线台站近高铁和远高铁监测点的谱比值来解释局部复杂场地条件对峰值加速度的影响,通过比较台站计算与设计的反应谱来预测高铁地震台站附近的桥梁震害情况。     

Land-sea correlations in the Australian region: 460 ka of changes recorded in a deep-sea core offshore Tasmania. Part 1: the pollen record

Long, well-dated records of climate change in Australia are rare because most of the continent is prone to deflation and sediments are difficult to date beyond 40?ka. Deep-sea cores, containing terrigenous material, provide an ideal alternative to terrestrial records, because of continuous sedimentation and a robust chronology derived from oxygen isotopes. In this paper, the first of a series of two, we present pollen and spores data from core Fr1/94-GC3 from the East Tasman Plateau. This core is positioned at the southern extreme of the East Australia Current and simultaneously records changes in both oceanography and environments both offshore and in southeastern Australia. In an area of slow sedimentation, this core provides a continuous record of vegetation change in southeastern Australia and the southern Tasman Sea over approximately the last half a million years. Through time, glacial periods have progressively become warmer and shorter. Alpine plant taxa become more restricted with time and rainforest taxa expand to a far more restricted degree during the present interglacial period than the previous one, representing a fundamental shift in the vegetation of Tasmania. We apply transfer functions to reconstruct past rainfall and land temperatures based on the palynoflora that are then compared against the marine proxy record.     

Sliding and overturning potential of Christchurch 2011 earthquake records

The 22 February 2011 M_w 6.3 earthquake produced a number of unique accelerograms in the city of Christchurch and the port of Lyttelton. Four of these records are analyzed in this paper. The two are from the Christchurch Catholic Cathedral College and Christchurch Hospital stations in the center of the city, which were placed on top of loose sandy soils that suffered softening due to liquefaction; one is from the Lyttelton station, Lyttelton Port Company, on a rock outcrop; and one is from the station at the Heathcote Valley Primary School, on stiff colluvial silts and sands near the edge of a steep and stiff sedimentary basin. The (elastic) response spectra are discussed and related to some salient characteristics of the motions. Symmetric and asymmetric sliding of a block resting through Coulomb friction on horizontal or inclined planes and rocking–overturning of rigid blocks, when excited at their base by these records, offer a strong indication of their ‘destructiveness potential’. The corresponding sliding and overturning spectra of the 2011 records are compared with those of some historic accelerograms to get an understanding of the severity of ground shaking that caused 170 deaths and heavy geotechnical and structural damage in the city of Christchurch. The possible role played by the unusually large vertical accelerations is also explored. Copyright © 2012 John Wiley & Sons, Ltd.     

Regional subsidence of Mexico City and its effects on seismic response

Changes expected in Mexico City's seismic response due to land subsidence caused by groundwater extraction are examined. Settlements of the land surface observed in the recent past are compiled and processed to predict regional subsidence in the near future. This information is used in combination with the iso-depth and iso-period maps stipulated by the building code to estimate the compaction of surface sediments and the shortening of soil periods. The time-progressive evolution of the official seismic zoning maps and the associated site-specific response spectra is predicted. The same is done with spectral response contours expressed in terms of the site and structure periods. The subsidence effects are considered through an impact factor, which represents the increase or decrease in the spectral ordinates with respect to the current values specified for design purposes. The detrimental or beneficial effects depend on the relative values of the structure and site periods.     

竖向与水平向地震动加速度反应谱比特性分析

本文采用全球范围128次地震的3235组三分量强地面运动记录,分析了其加速度竖向分量反应谱与水平分量反应谱的比值(V/H)的总体特征,研究了V/H随震级、震中距、局部场地条件和震源机制的变化关系。研究结果表明:(1)场地越硬,长周期段V/H越大,短周期段则相反;(2)震级越大,长周期段V/H越大,短周期段变化不明显;(3)短周期段V/H随震中距增大而减小;(4)对于大震(M7),长周期段V/H随震中距增大而减小;而对于中强震(M7),比值在近场(R60km)随震中距增加而增大,在远场则随震中距增加而减小;(5)V/H与震源机制也有一定的关系。     

中国大陆地震活动时空分布多重分形特征

利用多重分形分析方法,考察了中国大陆各构造区地震活动广义应变释放时间和空间分布的多重分形特征。结果表明,中国大陆各构造区地震活动广义应变释放时空分布的多重分形特征差别明显。